The invention relates to a self stopping or locking seat belt retractor with a housing having a blocking device that includes at least one blocking means for the belt shaft that can be controlled in a vehicle sensitive and/or belt sensitive manner into engagement with a toothed gearing system on the side of the housing, and a tightening device operating on the belt shaft comprising a drive wheel that can be set into rotation via a drive device, the drive wheel being connectable upon release of the tightening device with the belt shaft, whereby the drive wheel of the tightening device is connectable via the blocking device with the belt shaft for the transmission of force to the belt shaft and the drive wheel is, prior to the release of the tightening device, secured in a force-transmitting manner on the housing of the seat belt retractor.
A self stopping seat belt retractor with the above-noted features is described in EP 0 093 233. A rotation blade is provided to function as a drive wheel, the rotation blade being impinged by a gas stream introduced thereonto and being connected with a ring rotatably supported in a seat belt retractor housing. Pivotable bolts are arranged on the one side of the ring, the bolts being controllable into engagement with outer toothed lever gears fixedly secured to the belt shaft of the seat belt retractor so that, upon release of the tightening device, the rotatable ring drives the belt shaft via the bolts that have been controlled into engagement with the lever gear. At the same time, the ring is a component of a rotatably arranged housing and this ring is, during normal operation of the seat belt retractor without release of the tightening device, fixedly secured to the housing via a return movement stop, which is effective for stopping movement in the belt unwinding direction, that is in the form of stop levers engaging the housing. Upon blocking of the rotation of the belt shaft in the belt unwinding direction performed as a result of tasking by the belt-sensitive and/or vehicle-sensitive control system, the bolts between the ring and the lever gear are coupled to a control disk that is a component of the belt-sensitive/vehicle-sensitive control system, so that, upon tasking by the control system, the bolts disposed on the ring are controlled into engagement with the lever gear. In this manner the belt shaft is blocked in its rotational movement, whereby a loading on the belt shaft in the belt unwinding direction is diverted, via the belt shaft, the lever gear, the belt, and the ring with the housing, into the supporting housing of the seat belt retractor.
The state of the art seat belt retractor thus puts into effect the principle that the vehicle-sensitive and/or belt-sensitive controlled blocking device that is available in any event is now drawn into performing the additional function of, as well, coupling the drive wheel of the tightening device to the belt shaft for the tightening operation.
The invention provides a solution to the challenge of improving the functioning principle of a seat belt retractor having the state of the art features.